1. Technical Field
The present invention relates to vehicle aerodynamic structures and, more particularly, to a vehicle aerodynamic structure that accelerates an airflow passing under a floor of a vehicle that is traveling.
2. Related Art
When an automobile or other vehicle is running, an airflow passing under the floor of the vehicle is exposed to turbulence in a space between an inboard side of a tire and a vertical wall of a mud guard. Such turbulence causes an underfloor pressure in such a space to rise higher than that in a side sill, resulting in an airflow going to the outside of the vehicle. Such an airflow going to the outside of the vehicle turns to running resistance, causing such problems as worsened fuel economy and degraded running stability.
The following Japanese Unexamined Patent Application Publications (JP-A) describe an aerodynamic member disposed in the vicinity of a front tire to solve the problems described above.
JP-A. No. 2008-47146 discloses dimples formed on a vehicle fender to reduce air resistance inside the wheel house. As illustrated in FIG. 8, a plurality of dimples 102 are formed on the surface of an inner fender 100. With this arrangement, when the velocity of an airflow inside the wheel house reaches a predetermined level as a result of an increase in vehicle speed, the dimples 102 formed on the inner fender 100 change a laminar flow to a turbulent flow on a boundary layer close to the surface of the inner fender 100. As a result, the boundary layer's separation position is shifted downstream and leads to an increase in pressure in a low-pressure separation region that causes air resistance, thereby reducing etc resistance.
JP-A No. 2012-56499 discloses a vehicle flow straightening device for reducing an effect on a stream of air. Specifically, located in front of a tire 202, the vehicle flow straightening device 200 includes a flap 204 having a front face extending substantially laterally and vertically and a projection 206 that projects forward from the front face of the flap 204, as illustrated in FIG. 9. When a vehicle is running, the front face of the flap 204 changes the direction of an airflow passing along a surface to a direction in which contact of the airflow with a front tire and a lower arm that are disposed at the rear is avoided.